Hey Lads,

Maybe a dumb question but I just never noticed before.

Was just checking something on my gas cap and when I released it there was a pretty noticeable pressure noise. Couldn't tell if it was sucking or blowing but I suspect sucking from vacuum in the fuel tank.

I just wanted to check with you guys that some level of suction noise is normal?

It just struck me this morning that if the gas cap had failed and the tank couldn't balance to atmospheric, the fuel could get starved to the engine.

Bernie

 

Actually, the tank will implode before the engine completely starves for fuel. You might have a problem in your tank evaporative emissions venting system.

 

They all hiss when you open the cap. But if it is a lot you could have a problem. The cap has to seal to pass emissions tests.

 

mine doesn't, never has. The vent/evap system should prevent any "whooshing" IF functioning properly (known problem in Jaguars is a failed Rochester valve) properly operating vent/evap system should prevent vacuum pull in on tank under consumption and prevent pressure build up under heating of fuel. Think of a sealed can of gas in your driveway as it heats up in the sun and "swells" the can. Undesirable in cars, if your hearing hissing or wooshing the system is not working up to snuff.

 

+1